Id have to say the Beretta 92 it was in a ton of those 80-90's action films I grew up on and it still turns up in todays movies whether plain vanilla like in Die Hard or Lethal Weapon or Compensated and tricked out like in Robocop or Underworld it has literally been one of if not the biggest movie handgun of the past few decades.
My second choice would be Martin Lawrences "Little Earl" Glock 18 from National Security.
The Peacekeeper Rifles from Farscape.
Open range, best western since Josie Wales. The colt and scatter gun used to tame the west!